Many and various types of fluid conduits and pipe fittings for those conduits have been used in the past. In U.S. Pat. No. 5,183,298, of common assignee herewith, there are illustrated fittings for a fluid system wherein reducer fittings are employed with main fittings for reducing the flow in branch fluid flow conduits. In that patent, there is also illustrated a coupling system for securing the fittings to one another. More specifically, in that patent, a tee fitting is provided, with axially opposite end bells and a laterally directed bell, each bell having a pair of radially outwardly projecting, diametrically opposite, tabs or lugs. The reducer fitting to be joined to the tee similarly has a pair of radially outwardly projecting, diametrically opposed, tabs or lugs. When the reducer fitting is aligned with a bell on the tee, the lugs of the fittings are axially aligned with one another. Securing devices, such as a metal wrapping rings or straps, are applied to the registering lugs to secure the fittings to one another. These lugs and restraining rings are heavy-duty and designed to withstand thousands of pounds of pull per lug. Typically, on pipe fittings such as tees, reducers, bends and adapters, the lugs are cast on the fittings on opposite sides of the horizontal centerline of the flow passage through the fittings and only a pair of such lugs are provided each bell.
In many installations, it is often desirable to provide laterally directed fluid lines relative to a pair of generally parallel, horizontally extending, fluid lines. It will be appreciated that a fitting, such as a tee, may simply be installed so that its laterally directed opening (bell) extends to the desired side. However, where a second fluid line requires a lateral to extend to the same side as the first fluid line, the second tee cannot be installed to direct its lateral opening (bell) toward that one lateral side because the connection or the lateral pipe to the second tee would interfere with the other line. Thus, to direct laterals from a pair of parallel, generally horizontal pipe lines, the more remote pipe line must locate its lateral above or below the adjacent pipe line.
Various types of fittings have been provided for this purpose and involve a multiplicity of connections between a main line and a lateral line in order to locate the lateral above or below the main line. A number of different pipe connection assemblies have been required to effect that transition. These assemblies, however, not only require a substantial number of different parts but also extensive labor, resulting disadvantageously in prolonged installation. Further, when employing the system of restraining lugs disclosed in the above-identified patent, all of the lugs of the fittings, for example, tees and bends, are aligned in a plane containing the openings and the flow centerlines. Consequently, if a 90.degree. bend fitting is to be joined with a tee to produce a connection between a first line and a lateral at a different elevation, the lugs on the bell of the bend and the bell of the lateral of the tee are misaligned. More particularly, such lugs are misaligned by 90.degree. and the desired connection cannot be effected using the restraints and aligned lugs as set forth in that prior U.S. Pat. No. 5,183,298. Thus, it has been found desirable to provide a pipe coupling which will facilitate the connection between a main line and a lateral line using a lug and restraint system, as exemplified in U.S. Pat. No. 5,183,298, for joining pipe lines at different elevations relative to one another.